1. Field of the Invention
The present invention relates to an antenna for mobile wireless communications mainly used by a portable telephone or the like, and to a portable-type wireless apparatus.
2. Description of the Related Art
In recent years, technology relating to the portable telephone or the like has rapidly been developing. In a portable telephone terminal, an antenna is one of specially important devices and, accompanied by the miniaturization of the terminal, the antenna is also required to be miniaturized and built-in.
One example of the above described conventional antenna for mobile wireless communications will be described with reference to the accompanied drawing.
The conventional antenna for mobile wireless communications is shown in FIG. 21. 201 is a planar antenna element, 202 a feeding point, 203, 204 metal wires and 205 a conductive ground plate. The antenna element 201 is fed from a feeding point 202 via the metal wire 203. Also, the antenna element 201 is connected to the conductive ground plate 205 via the metal wire 204.
This is usually referred to as Planar Inverted F Antenna PIFA and used in a portable terminal as a short and small size antenna. The radiation characteristic thereof is shown in FIG. 22.
However, since the above described configuration results in an unbalanced-type antenna, a large current flows into the ground plate 205 forming a body of apparatus, which acts as an antenna. A drawing typically showing the current at this time is shown in FIG. 23. In this case, when the human body grips the body of apparatus, the input impedance of the antenna is changed greatly so that the radiation characteristics are deteriorated.
In view of the problems in the above described conventional antenna, an object of the present invention is to provide an antenna for mobile wireless communications and a portable-type wireless apparatus using the same in which the current of the body of apparatus is reduced and the effect of the human body on the radiation characteristics is minimized much more.
One aspect of the present invention is an antenna for mobile wireless communications, comprising two antennas, wherein feeding phases for said two antennas are substantially different with each other.
Another aspect of the present invention is the antenna for mobile wireless communications, wherein the difference of the feeding phases between said two antennas is substantially 180 degrees.
Still another aspect of the present invention is the antenna for mobile wireless communications, wherein said two antennas are arranged in close vicinity to an ground plate.
Yet another aspect of the present invention is the antenna for mobile wireless communications, wherein said two antennas are of the same shape, and moreover, the ambient lengths of the respective two antennas are either the same or different with each other.
Still yet another aspect of the present invention is the antenna for mobile wireless communications, wherein said two antennas are arranged in the location where they become substantially axi-symmetric.
A further aspect of the present invention is the antenna for mobile wireless communications, comprising feeding points connected to each antenna, wherein each of said two antennas is in the shape of a polygon or a circle and each of said two antennas is configured by a metal plate electrically short-circuited with said ground plate at least at one place.
A still further aspect of the present invention is the antenna for mobile wireless communications, comprising the feeding points connected to each antenna, wherein each of said two antennas is in the shape of a polygon or a circle and each of said two antennas is configured by the metal plates electrically short-circuited with said ground plate at least at one place.
A yet further aspect of the present invention is the antenna for wireless communications, wherein slits are disposed with said metal plates at least at one place.
A still yet further aspect of the present invention is the antenna for wireless communications, wherein a switching circuit capable of electrically connecting an open end of the slit is connected to said slit.
An additional aspect of the present invention is the antenna for mobile wireless communications, wherein said switching circuit is configured by a series resonance circuit.
A sill additional aspect of the present invention is the antenna for mobile wireless communications, wherein said switching circuit is configured by a parallel resonance circuit.
A yet additional aspect of the present invention is the antenna for mobile wireless communications, wherein said two antenna are formed on a dielectric substrate.
A still yet additional aspect of the present invention is an antenna for mobile wireless communications, comprising:
a conductive ground plate of a substantially rectangular shape;
a dielectric substrate arranged on said conductive ground plate in close vicinity to the other end portion side of said both end portions with the center location of the longitudinal conductive ground plate as a basis; and
two antenna elements of a substantially rectangular shape formed on said dielectric substrate,
wherein each of said two antennas has a feeding point and at least one through-hole and is electrically short-circuited with said conductive ground plate by the through-hole.
Another aspect of the present invention is the antenna for mobile wireless communications, wherein the difference of the feeding phases for said two antenna elements is substantially 180 degrees.
Still another aspect of the present invention is the antenna for mobile wireless communications, wherein said two antenna elements are substantially of an axi-symmetric structure.
Yet another aspect of the present invention is the antenna for mobile wireless communications, wherein each said feeding point and each said through-hole is arranged at the location where either of them becomes axi-symmetric.
Still yet another aspect of the present invention is the antenna for mobile wireless communications, wherein a distance between said two antennas or a distance between said two antenna elements is a length not greater than one-tenth of a wavelength corresponding to a length which is substantially two times an ambient length of each said antenna or each said antenna element.
A further aspect of the present invention is the antenna for mobile wireless communications, wherein each said feeding point and each said through-hole is arranged in the location where either of them becomes axi-symmetric.
A yet further aspect of the present invention is the antenna for mobile wireless communications, wherein a distance between said two antennas or a distance between said two antenna elements is a length not greater than one-tenth of a wavelength corresponding to a length which is substantially two times an ambient length of each said antenna or each said antenna element.
A still yet a further aspect of the present invention is the antenna for mobile wireless communications, wherein each said feeding point and each said through-hole is arranged at the location where either of them becomes axi-symmetric.
An additional aspect of the present invention is the antenna for mobile wireless communications, wherein a distance between said two antennas or a distance between said two antenna elements is a length not greater than one-tenth of a wavelength corresponding to a length which is substantially two times an ambient length of each said antenna or each said antenna element.
A still additional aspect of the present invention is the antenna for mobile wireless communications, further comprising a balance-to-unbalance circuit for feeding said two antennas or said two antenna elements.
A yet additional aspect of the present invention-is the antenna for mobile wireless communications, wherein each said metal plate is of a rectangular shape and each portion in which each of said two metal plates arranged in a substantially axi-symmetric location is electrically short-circuited with said ground plate is inclose vicinity to an outer peripheral portion of said metal plate.
A still yet additional aspect of the present invention is the antenna for mobile wireless communications, wherein each said metal plate is of a rectangular shape and each portion in which each of said two metal plates arranged in a substantially axi-symmetric location is electrically short-circuited with said ground plate is inclose vicinity to the outer peripheral portion of said metal plate.
Another aspect of the present invention is the antenna for mobile wireless communications, wherein said portion is in close vicinity to a side opposite to each of respective sides where said metal plates arranged in said axi-symmetry stand face to face each other and, viewed from said portion, each said antenna is fed from the feeding point in close vicinity to a central portion of said metal plate.
Still another aspect of the present invention is the antenna for mobile wireless communications, wherein said portion is in close vicinity to a side opposite to each of respective sides where said metal plates arranged in said axi-symmetry stand face to face each other and, viewed from said portion, each said antenna is fed from the feeding point in close vicinity to a central portion of said metal plate.
Yet another aspect of the present invention is the antenna for mobile wireless communications, wherein said two antennas are arranged by inclining to one of both sides with the central portion of said ground plate as a basis, and each said portion and each said feeding point is arranged in close vicinity to said one side.
Yet still another aspect of the present invention is the antenna for mobile wireless communications, wherein said two antennas are arranged by inclining to one of both sides with the central portion of said ground plate as a basis, and each said portion and each said feeding point is arranged in close vicinity to said one side.
A further aspect of the present invention is the antenna for mobile wireless communications, wherein said two antennas are formed on a dielectric.
A still further aspect of the present invention is the antenna for mobile wireless communications, wherein said two antennas are formed on the dielectric.
A yet further aspect of the present invention is the antenna for mobile wireless communications inventions, wherein an operating frequency band is above UHF band.
A still yet further aspect of the present invention is the antenna for mobile wireless communications inventions, wherein an operating frequency band is above UHF band.
An additional aspect of the-present invention is the antenna for mobile wireless communications inventions, wherein an operating frequency band is above UHF band.
A still additional aspect of the present invention is a portable-type wireless apparatus, comprising an antenna for mobile wireless communications using said ground plane as a ground plate on a dielectric circuit substrate having a ground plane, wherein said dielectric circuit substrate and said antennas or antenna elements are covered with a case made of resin.
A yet additional aspect of the present invention is a portable-type wireless apparatus, comprising an antenna for mobile wireless communications using said ground plane as a ground plate on a dielectric circuit substrate having a ground plane, wherein said dielectric circuit substrate and said antenna or antenna elements are covered with a case of resin.
A still yet additional aspect of the present invention is a portable-type wireless apparatus, comprising an antenna for mobile wireless communications using said ground plane as a ground plate on a dielectric circuit substrate having a ground plane, wherein said dielectric circuit substrate and said antennas or antenna elements are covered with a case made of resin.